1. Unit 2: Chain Surveying
25 November 08
Unit 2 :Chain Surveying

2. Topics covered
Different methods for linear measurement, instruments for chaining
Different types of Chains/Tapes
Ranging - Direct, Indirect, chaining on sloping ground
Chain surveying: survey station, survey line, locating the ground features with the help of offsets.
Chain surveying, fieldwork & office work
25 November 08
Unit 2 :Chain Surveying

3. 2.1 Linear measurement- Basics
One of the basic function in surveying
Always horizontal not sloping distance
No way to check the error other than remeasuring A B
Inclined distance AB is not correct
Horizontal distance is correct
Mention about the greater area of land when purchase on the sloping ground.
Measurement should be made very carefully as there is no means of checking if it is accurate or not?
25 November 08
Unit 2 :Chain Surveying

4. 2.1 Linear measurement methods
Electronic methods
By optical means
Direct measurements
25 November 08
Unit 2 :Chain Surveying

5. 2.1 Direct measurements Instruments such as
Pacing
Passometer
Pedometer
Odometer or Speedometer
Rough methods for preliminary survey
Check of large mistakes in measurement made by more precise method
Unsuitable in irregular and sloping ground
Precision – 1/50 to 1/200
25 November 08
Unit 2 :Chain Surveying

6. 2.1 Taping / Chaining Chaining or taping carries same meaning
Use of either chain or tape.
One of the accurate method of direct measurements
This method is basis for most surveying.
Precision
1/1000 to 1/5000 (ordinary land survey)
Use of chain or tape
Chain (Early 1600s)
Steel tape in use by early 2000s
Tape is very common nowadays.
25 November 08
Unit 2 :Chain Surveying

7. 2.1 Instruments for chaining/taping
Chain/tape
Arrows
pegs
Ranging rods
Plumb bob
Hand level
25 November 08
Unit 2 :Chain Surveying

8. 2.1 Instruments for chaining/taping
Contd….
Arrows
10 arrows
Pegs
Station position
Terminal points of survey line
25 November 08
Unit 2 :Chain Surveying

9. 2.1 Instruments for chaining/taping
Contd….
Ranging rods
Used to range intermediate points on survey line
Length 2 m ( very common) or 3 m
Bands of 20 cm painted alternate colour( red & white, black & white)
Ranging poles
Similar to ranging rod but big in size
Used in case of long lines
25 November 08
Unit 2 :Chain Surveying

10. 2.1 Instruments for chaining/taping
Contd….
Plumb bob
Verticality of ranging pole
Transferring the points to ground
Also used for centring purpose in other surveying methods.
25 November 08
Unit 2 :Chain Surveying

11. 2.2 Different types of chain/tape
Chain (Absolute equipment at present)
Metric chain (available in 5,10,20 meter)
Gunter’s or surveyor’s chain (66 ft of 100 links)
Engineer’s chain (100 ft of 100 links)
Revenue chain (33 ft of 16 links)
Steel band or band chain ( 20 or 30 m)
25 November 08
Unit 2 :Chain Surveying

12. 2.2 Different types of chain/tape
Contd….
Tape
Cloth or Lenin tape
Metallic tape
Steel tape
Invar tape (Alloy of nickel 36% & steel)
Steel Tape
Linen Tape
Metallic Tape
Cloth Tape
25 November 08
Unit 2 :Chain Surveying

13. 2.3 Ranging
When the length of survey line is greater than chain or tape length
Process of establishing intermediate points
Methods
Direct Ranging
Indirect Ranging
Intermediate points
> one tape length B A
25 November 08
Unit 2 :Chain Surveying

14. 2.3 Direct ranging Direct ranging When two end points are intervisible
Either by eye or through optical instruments such as
Line ranger
Theodolite
Code of signals used to direct assistant A P B
Transverse movement
< one tape length
25 November 08
Unit 2 :Chain Surveying

15. 2.3 Indirect ranging Indirect ranging
When two end points are not intervisible
With the aid of two intermediate points very near to the line M N A B M N M3 B A N3 M2
N 2 N1 M1
25 November 08
Unit 2 :Chain Surveying

16. 2.3 Chaining/taping over sloping ground
Methods
Direct method or method of stepping
Indirect method
With the aid of vertical angle measurement
With the aid of difference in level measurement
Hypotenusal allowance
25 November 08
Unit 2 :Chain Surveying

17. 2.3 Chaining/taping over sloping ground
Contd….
Direct method or stepping method
Convenient to proceed down-hill
Tape shall be horizontal
Sufficient pull to avoid sag
Lengths of steps inversely proportion to degree of slopes. A B l4 l3 l2 l1
D = (l1+l2+l3+l4)
25 November 08
Unit 2 :Chain Surveying

18. 2.3 Chaining/taping over sloping ground
Contd….
Indirect method (Vertical angle measured)
Clinometer to measure vertical angle D2 Φ1 Φ2 s1 s2 C B A D1
D1 = s1×cosΦ1
The required horizontal distance (D) =∑s cosΦ
Indirect method (difference in height)
Level machine is used to measure h to compute D. D h s A B C
D = √( s 2 - h 2 )
Indirect method (Hypotensual allowance) B A’ C A θ
1 chain
BA / = BC = 1 CHAIN
BA = 1 CHAIN × sec θ
AA / = BA - BA / = 1 CHAIN ( sec θ – 1)
25 November 08
Unit 2 :Chain Surveying

19. 2.4 Chain surveying What is chain surveying?
Principle of chain surveying
Triangulation
Survey stations
Main station (A, B, C,…E)
Subsidiary stations (F, G, H)
Marking of stations
Survey lines
Main survey lines
Base lines
Check lines
Tie lines
25 November 08
Unit 2 :Chain Surveying

20. 2.4 Survey stations & survey lines
Mutually visible
Survey lines
Few as far as possible
Must have one base line
Pass through level ground
Form well-conditioned triangle
Sufficient check line
Short offset
Should not pass through obstacle
Should fall within the boundaries
25 November 08
Unit 2 :Chain Surveying

21. 2.4 Locating the ground features
Offsets- lateral distance of an object from survey line.
Offsets should be as small as possible
Types
Perpendicular – less measuring on ground
Oblique
Method of ties A C P B
900 B A P C
≠ 900 P Q
25 November 08
Unit 2 :Chain Surveying

22. 2.4 Locating the ground features
Contd….
Swing of the tape on chain line
Shortest distance is perpendicular offset P
25 November 08
Unit 2 :Chain Surveying

23. 2.4 Locating the ground features
Contd….
Offsets are taken in the order of their chaninage.
Number of offsets depends upon the shape of objects
Straight wall, zigzag wall, road with constant width
Boundary wall
Constant width road
25 November 08
Unit 2 :Chain Surveying

24. 2.4 Locating the ground features
Contd….
25 November 08
Unit 2 :Chain Surveying

25. 2.5 Chain surveying (field/office work)
Equipment
Chain/Tape (>30 m)
10 Arrows
Raging rods
A tape ( 10 m or 20 m )
Cross staff or Optical square
Field book, pencil
Plumb bob
Pegs, wooden hammer, chalks
25 November 08
Unit 2 :Chain Surveying

26. 2.5 Field work Field work consists of three steps Reconnaissance
Marking and fixing survey stations
Running survey lines
Reconnaissance
Walkover survey with the view of principle of surveying
Reference sketch
Thinking of possible problem and their solution in actual survey
25 November 08
Unit 2 :Chain Surveying

27. 2.5 Field work
Contd….
Purpose is to enable to locate stations during progress of work
Wooden pegs in soft ground
Nails or spikes in hard surface (road) & flushed with pavement
For a long time used station, a stone of standard size fixed with mortar
Reference of two or three permanent object
Chaupari
Building
Electric pole
9.65m
10.50m
9.90m
25 November 08
Unit 2 :Chain Surveying

28. 2.5 Field work Start chaining from base line Consists of two folds
Contd….
Start chaining from base line
Consists of two folds
Chain the survey line
Locate the adjacent details
Chaupari
One tape length
Building
25 November 08
Unit 2 :Chain Surveying

29. 2.5 Field work
Contd….
25 November 08
Unit 2 :Chain Surveying

30. 2.5 Office work Part of office work Computation of data Plotting work
Size of paper should be standard (in mm)
A0 = 840 * 1188
A1 = 594 * 840
A2 = 594 * 420
A3 = 420 * 297
A4 = 297 * 210
25 November 08
Unit 2 :Chain Surveying

31. 2.5 Plotting work Fix the scale of survey before starting
Purpose of survey
Extent of survey
Finance available
North upward rule
Nice lettering (Always in the drawing)
Skeleton first then offsets
Use of tracing paper for proper orientation
Put the details of title and legend box in the slide
25 November 08
Unit 2 :Chain Surveying

32. 2.5 Plotting work Start with base line
Triangles are laid by intersection of arcs
Verification of check lines
Offsets are then plotted by
Set square or
Offset scale
Ground features representation with symbol
Title box and legend box
Use of HB, 2H and 3H pencils
Put the details of title and legend box in the slide
25 November 08
Unit 2 :Chain Surveying

33. Conventional symbols
25 November 08
Unit 2 :Chain Surveying

34. Conventional symbols
Contd….
25 November 08
Unit 2 :Chain Surveying

35. Thank you for your attention!
Any questions? Querries?
25 November 08
Unit 2 :Chain Surveying